Pipetting device



Dec. 13, 1966 A. R. PURSELL PIPETTING DEVICE Filed May 25, 1964INVENTOR. Allied H. Purs ell riam;

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United States Patent 3,290,946 PIPETTING DEVICE Alfred R. Pursell,Indianapolis, Ind, assignor to The Dow Chemical Company, Midland, Mich.,a corporation of Delaware Filed May 25, 1964, Ser. No. 369,865 7 Claims.(Cl. 73--425.6)

The invention relates to a manually operated device for drawing a liquidinto a pipette.

It has long been a desideratum in the art to provide a manual device forfilling pipettes which will satisfactorily replace pipetting by mouthand its attendant dangers. The devices as known to the prior art havegenerally suflered from the disadvantage that they must be disconnectedif the pipette is to be discharged by gravity flow and controlled by thefingertip of the operator for maximum accuracy. Devices which are notdesigned to be disconnected before discharging the pipette generallyoperate so as to discharge a fixed volume or will discharge variedvolumes as desired only on making a cumbersome change in parts orfittings or settings.

It is, therefore, a principal object of the invention to provide apipetting device for the manual filling of a pipette which overcomes thedisadvantages of the prior art devices.

A specific object of the invention is to provide a pipetting devicebywhich a pipette is manually filled but which permits fingertip controlof the discharge of the pipette without disconnecting the device fromthe pipette.

Another specific object of the invention is to provide a pipettingdevice which permits the operator to mix the sample, employing theassembled pipette device, and thereafter to fill the pipette withoutchanging the assembly.

A further specific object of the invention is .to provide a manualpipetting device which is conveniently suited to repetitive or volumework, whether uniform or varied amounts are to be dispensed.

Another object of the invention is .to provide a manual pipetting devicewhich is flexible enough in operation to permit fingertip control ofgravity flow discharge of the pipette without disengaging the device orto accomplish blowout delivery from the pipette if desired.

These and other objects and advantages of the invention will be moreclearly understood on becoming more familiar with the followingdescription and claims and the appended drawings in which like numeralsidentify like parts.

FIG. 1 is a sectional view in side elevation of the pipetting device ofthe invention having a pipette operatively attached, and

FIG. 2 is a sectional view in side elevation of a different embodimentof the invention showing only the plunger and barrel with spring returnmeans disposed inside the barrel, and

FIG. 3 is a sectional view similar to FIG. 2 showing the plunger andbarrel of the device and illustrating different means for attaching andemploying the spring means, and

FIG. 4 is a sectional view similar to FIG. 3 showing another means forlimiting the outward movement of the plunger, and

FIG. 5 is a fragmentary sectional view showing another means ofassemblying the plunger.

The pipetting device as shown in FIG. 1 consists broadly of a hollowplunger 10, a complementary barrel 11, spring means 12 adapted to urgethe plunger outward ly of the barrel 11 throughout a substantial strokerela tive to the barrel, and an adapter 13 connected to the dispensingend 14 of the barrel. There are provided, as essential features, anopening 15 through the finger-engaging end 16 of the plunger 10, anopening 17 through the lower end 18 of the plunger 10 and an opening 19,through the dispensing end 14 of the barrel 11, which communicates witha channel 20 through the adapter 13 which in turn communicates with thepipette receiving opening or cavity 21 in the adapter 13.

If desired, the hollow plunger 10 may be provided with O-ring means 22to provide a good resilient seal between the plunger 10 and the barrel11. Also, any suitable pipette attaching means may be employed in placeof adapter 13. For example, in place of the adapter shown in FIG. 1,there may be employed a Luer-lok connector if pipettes are employedhaving the appropriate top to engage such a connector. Or, if desired,the adapter may be in the form of a standard tapered glass joint in theevent pipettes having ground tapered tops are employed. The adapter maybe attached in any suitable manner: by a threadable connection, as shownin FIG. 1; by employing resilient material as the body of the adapterwhich slides onto the barrel; or by rigidly attaching the adapter to thebarrel in a more permanent manner as by sealing or cementing.

In another embodiment of the invention as shown in FIG. 2, spring means23 is disposed inside the barrel 11 below the end 18 of the plunger 10.Placing the spring inside the barrel has the advantage that it is notcontacted by the hands of the operator so as to interfere in any mannerwith the manual operation of the pipette.

The embodiment of the device shown in FIG. 3 is provided with springmeans 24 which performs two functions. The spring means 24 resilientlyurges plunger 10 outwardly from barrel 11 but limits the outwardmovement of the plunger upon the spring reaching its normal uncompressedstate. The spring means 24, as shown retains the plunger 10 by havingone end 25 of the spring 24 wrapped around the barrel 11 below theflange 26 thereof and by having the other end 27 of the spring means 24wrapped one or two turns around the plunger 10 above the flanged top 28thereof. This embodiment of the device with retaining means provides theadvantage that the plunger cannot fly completely out of the barrel ifthe operators finger should slip from the top of the plunger while thespring is in the compressed condition.

In FIG. 4, there is illustrated another embodiment of the plunger andbarrel portion of the invention in which a different retaining means isused to prevent untimely flight of the plunger. In this embodiment, theplunger indicated generally by the numeral 10 is provided with a smallershank portion 29 adjacent the finger-engaging flanged top 16 and anenlarged lower portion 30 disposed within the barrel 11 and adapted tosealingly and slideably engage the walls thereof.

In order to fabricate a plunger-barrel combination with this type ofretaining means, it is necessary to provide means of manufacturing andassembling the parts, As shown, the enlarged portion 30 of the plunger10 is threadably attached to the smaller portion 29. The plunger isbrought into the barrel through the dispensing end 14 which isthereafter substantially closed by a plug 31, which threadablyfastens inplace inside the end 14 and is provided with an opening 19 therethroughsimilar to the other embodiments. In another manner of assembling theapparatus with this type of retaining means, the finger-engaging end 16of the plunger 10 is threadably attached, as shown in FIG. 5, to thesmaller shank portion 29 in lieu of the threadable connection to thelarger plunger portion 30 as shown in FIG. 41. The embodiments asillustrated in FIGS. 4 and 5 have the advantage that the extent ofreciprocated motion of the plunger 10 is precisely limited and notsubject to substantial change as might occur if the spring means 24should become substantially elongated permanently.

The apparatus may also be provided, if desired, with a biological filter32 disposed transversely across the end of the opening 19 in thedispensing end 14 of the barrel 11 so as to filter all fluid, air orliquid passing through the opening 19.

The plunger and barrel of the apparatus of the invention may be preparedfrom any material which is suitably fabricated and which is notstructurally deformed by sterilization techniques, e.g., autoclaving.Thus, the plunger and barrel will customarily be made of glass orstainless steel or aluminum or heat resistant polymeric material. Thespring means is made of corrosion resistant steel, preferably stainlesssteel. The adapter is made of any suitable material appropriate to thedesign employed. The adapter shown can be made of metal or glass, orheat resistant, flexible, polymeric material. A Luer-lok type connector,of course, can be made of stainless steel, while a standard taperedjoint connection will usually be made of glass but may be made of metalif desired.

In operating the present pipetting device, the device is ordinarilygrasped about the barrel between the thumb and middle finger, ringfinger and little finger, leaving the index finger free for theoperation of the plunger. A pipette is inserted into or operativelyattached to the adapter. The index finger is brought down upon thefinger-engaging top of the plunger so as to depress the plunger into thebarrel. The pipette is inserted in the liquid to be sampled. If it isdesired to mix the liquid, as is frequently desired in serological work,the index finger is placed sealingly over the opening in thefingerengaging end of the plunger and the plunger is reciprocated up anddown several times. If it is desired not to disturb or mix the liquid,the index finger may be rolled slightly to one side so as not to closethe opening in the plunger. When the operator is ready to fill thepipette, the index finger is placed or maintained sealingly over theopening in the finger-engaging end of the plunger and the plunger isallowed to move out of the barrel under the urging of the compressedspring means. When the pipette has filled somewhat above thepredetermined mark or graduation, the operator simply releases the indexfinger pressure momentarily so that the plunger rises to the normalposition of rest, i.e., with the spring no longer compressed, while theindex finger is removed momentarily from the opening in the plunger soas not to draw up more liquid into the pipette. The operator then bringsthe index finger into sealing relationship with the opening in the topof the plunger, raises the pipette out of the liquid and proceeds topipette as is customary with normal mouth pipetting.

Among the advantages of the assembly is the fact that it is used withthe same hand movements as the common laboratory pipettes now in use,and it is thus easy for technicians to readily acquire facility in theuse of the apparatus.

The apparatus of the invention having been thus fully described,modifications thereof will at once be apparent to those skilled in theart, and the scope of the invention is to be considered limited only bythe claims appended hereinafter.

I claim:

1. In a syringe employed as a manual pipette filling and dispensingdevice and having a hollow cylindrical plunger and a complementarybarrel, said plunger and barrel fitting together in sliding, sealingrelation, and said barrel having a dispensing end, the improvement which'consists in:

(a) spring means adapted to resiliently urge the plunger outwardly ofthe barrel of the syringe throughout a substantial stroke relative tothe barrel;

(b) an adapter sealingly attached to the dispensing end of the barrel,said adapter being adapted to receive and hold a pipette in sealingrelationship in an opening therein;

(c) and a first opening through the finger-engaging top of the plungerfor fingertip control of dispensing, said first opening communicatingthrough the hollow plunger with a second opening provided through thebottom of the plunger, said second opening in turn communicating throughthe barrel with an opening through the dispensing end of said barrel,and said opening through the dispensing end of the barrel communicatingwith a channel in the adapter which communicates with the pipettereceptive openmg.

2. The improvement as in claim 1 in which the spring means is disposedinside the barrel of the syringe.

3. The improvement as in claim 1 in which the spring means is disposedaround the plunger of the syringe and external to the barrel.

4. The improvement as in claim 3 in which the outward movement of theplunger is limited by attaching the spring means to the barrel and tothe finger-engaging top of the plunger.

5. The improvement as in claim 3 in which the outward movement of theplunger is limited by the plunger having a smaller upper portion, and anenlarged lower portion, said lower portion being disposed slideablywithin the barrel and retained therein by an inwardly extending flangecomprising the upper end of the barrel.

6. The improvement as in claim 1 having a biological filter disposedbetween the adapter and the dispensing end of the barrel of the syringeso as to filter all fluid passing through the dispensing end of thebarrel.

7. An improved manual pipette filling and dispensing device whichcomprises:

a syringe comprising a hollow cylindrical plunger and a complementarybarrel, said plunger having a finger-engaging top, a shank portionhaving a lower end, and said barrel having a dispensing end and aplunger receiving end, and said barrel receiving said plunger insliding, sealing relation;

spring means disposed in conjunction with said plunger and said barrelso as to resiliently urge the plunger outwardly of the barrel throughouta substantial stroke of the plunger relative to the barrel;

an adapter sealingly attached to the dispensing end of the barrel, saidadapter having a channel therethrough, said channel communicating withan opening in the adapter, said adapter being adapted to receive andhold a pipette in sealing relationship in said opening;

a first opening through the finger-engaging top of the plunger forfingertip control of dispensing, said first opening communicatingthrough the hollow plunger with a second opening provided through thebottom of the plunger, said second opening in turn communicating throughthe barrel with an opening through the dispensing end of the barrel, andsaid opening through the dispensing end of the barrel communicating withsaid channel in the adapter which communicates with the pipettereceptive opening.

References Cited by the Examiner UNITED STATES PATENTS 2,335,049 11/1943Finkelstein 73425.6 2,410,552 11/1946 Rosen 73425.6

FOREIGN PATENTS 914,790 7/1954 Germany.

LOUIS R. PRINCE, Primary Examiner.

DANIEL M. YASICH, Assistant Examiner.

1. IN A SYRINGE EMPLOYED AS A MANUAL PIPETTE FILLING AND DISPENSINGDEVICE AND HAVING A HOLLOW CYLINDRICAL PLUNGER AND A COMPLEMENTARYBARREL, SAID PLUNGER AND BARREL FITTING TOGETHER IN SLIDING, SEALINGRELATION, AND SAID BARREL HAVING A DISPENSING END, THE IMPROVEMENT WHICHCONSISTS IN: (A) SPRING MEANS ADAPTED TO RESILIENTLY URGE THE PLUNGEROUTWARDLY OF THE BARREL OF THE SYRINGE THROUGHOUT A SUBSTANTIAL STROKERELATIVE TO THE BARREL; (B) AN ADAPTER SEALINGLY ATTACHED TO THEDISPENSING END OF THE BARREL, SAID ADAPTER BEING ADAPTED TO RECEIVER ANDHOLD A PIPETTE IN SEALING RELATIONSHIP IN AN OPENING THEREIN; (C) AND AFIRST OPENING THROUGH THE FINGER-ENGAGING TOP OF THE PLUNGER FORFINGERTIP CONTROL OF DISPENSING, SAID FIRST OPENING COMMUNICATINGTHROUGH THE HOLLOW PLUNGER WITH A SECOND OPENING PROVIDED THROUGH THEBOTTOM OF THE PLUNGER, SAID SECOND OPENING IN TURN COMMUNICATING THROUGHTHE BARREL WTIH AN OPENING THROUGH THE DISPENSING END OF SAID BARREL,AND SAID OPENING THROUGH THE DISPENSING END OF THE BARREL COMMUNICATINGWITH A CHANNEL IN THE ADPATER WHICH COMMUNICATES WITH THE PIPETTERECEPTIVE OPENING.